clock: add a method to obtain the configuration.

This function allows the ports to read configuration variables without
changing the port method signatures.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>

clock.c

@@ -755,6 +755,11 @@ UInteger8 clock_class(struct clock *c)
 	return c->dds.clockQuality.clockClass;
 }
 
+struct config *clock_config(struct clock *c)
+{
+	return c->config;
+}
+
 static int clock_add_port(struct clock *c, int phc_index,
 			  enum timestamp_type timestamping,
 			  struct interface *iface)

clock.h

@@ -57,6 +57,13 @@ struct port *clock_best_port(struct clock *c);
  */
 UInteger8 clock_class(struct clock *c);
 
+/**
+ * Obtains a reference to the configuration database.
+ * @param c  The clock instance.
+ * @return   A pointer to the configuration, without fail.
+ */
+struct config *clock_config(struct clock *c);
+
 /**
  * Create a clock instance. There can only be one clock in any system,
  * so subsequent calls will destroy the previous clock instance.